The major goal of the Neuropathology (NP) Core is to provide researchers with well characterized and preserved brain tissue and diagnostic neuropathology evaluations for Alzheimer's Disease (AD) patients and controls. Provision of such tissue is essential to the overall goal of the ADCC to promote strong scientific investigations of AD. In order to achieve this goal, the NP Core will carry out the following specific tasks: 1. obtain brain tissue from AD and control patients who have undergone multiple annual neuropsychological and neurological evaluations prior to death; 2. preserve the tissue in a variety of ways in order to allow application of the most up-to-date technologies by researchers; 3. apply standard criteria for the diagnosis of AD to these brains in a consistent fashion and provide a thorough neuropathological evaluation; 4. maintain an awareness of controversies and evolving standards in the diagnostic criteria; 3. store brain tissue and neuropathological data in a reliable way allowing rapid retrieval; and 6. encourage use of resources of the NP Core by researchers through tissue and data accessibility and accommodation of special preservation protocols. To improve access to well-studied control tissue, the ADCC has established the Religious Orders Study (ROS) Core. The NP Core has begun to obtain brain tissue (19 cases so far) from study subjects who have undergone careful neurological and neuropsychological follow-up. This tissue is likely to be especially valuable in making rigorous clinical- pathological correlations. The NP Core proposes to provide investigators with tissue from this a stereological quantitation of PHF-tau immunostained neuritic plaques and neurofibrillary tangles in the frontal, temporal, and parietal cortices, hippocampus, and entorhinal cortex of-tissue from the ROS core subjects, with the goals of further characterizing the interface between Alzheimer's disease and aging changes in the brain and evaluating stereologic technology as a potential tool to assist in diagnostic classification of this area.